In order to machine an internal surface of a work piece, such as but not limited to a differential case, special purpose machines with a high initial cost. Additionally, these special purpose machines require service by specially trained personnel when they go down making them expensive to maintain. As a result, the conventional special purpose machines for machining the internal surface of a differential case increase the overall costs associated with manufacturing a differential case. It would therefore be advantageous to develop an apparatus and method for machining an internal surface of a work piece that reduces the overall costs associated with manufacturing the work piece.